Wednesday, 9 August 2017

“Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes, caused by "excessive nutrient pollution from human activities coupled with other factors that deplete the oxygen required to support most marine life in bottom and near-bottom water.” [US National Ocean and Atmospheric Administration]

Every Northern Hemisphere Spring this dead zone occurs in the Gulf of Mexico and increases in size over time.

Oxygen-starved coastal waters are rapidly increasing in prevalence worldwide. However, little is known about the impacts of these “dead zones” in tropical ecosystems or their potential threat to coral reefs. We document the deleterious effects of such an anoxic event on coral habitat and biodiversity, and show that the risk of dead-zone events to reefs worldwide likely has been seriously underestimated. Awareness of, and research on, reef hypoxia is needed to address the threat posed by dead zones to coral reefs.

Degradation of coastal water quality in the form of low dissolved oxygen levels (hypoxia) can harm biodiversity, ecosystem function, and human wellbeing. Extreme hypoxic conditions along the coast, leading to what are often referred to as “dead zones,” are known primarily from temperate regions. However, little is known about the potential threat of hypoxia in the tropics, even though the known risk factors, including eutrophication and elevated temperatures, are common. Here we document an unprecedented hypoxic event on the Caribbean coast of Panama and assess the risk of dead zones to coral reefs worldwide. The event caused coral bleaching and massive mortality of corals and other reef-associated organisms, but observed shifts in community structure combined with laboratory experiments revealed that not all coral species are equally sensitive to hypoxia. Analyses of global databases showed that coral reefs are associated with more than half of the known tropical dead zones worldwide, with >10% of all coral reefs at elevated risk for hypoxia based on local and global risk factors. Hypoxic events in the tropics and associated mortality events have likely been underreported, perhaps by an order of magnitude, because of the lack of local scientific capacity for their detection. Monitoring and management plans for coral reef resilience should incorporate the growing threat of coastal hypoxia and include support for increased detection and research capacity.

Anyone still in favour of allowing an expansion of coal mining in the Galilee Basin, Queensland?

Anyone still comfortable with the amount of agricultural/industrial run-off into the Great Barrier Reef, marine protected areas and Australian coastal waters, which is allowed under state and federal policies?

It’s not just our rivers and aquifers which are suffering from political inaction and vested interest greed.

A reduction in dissolved oxygen concentrations is amongst the most important effects of eutrophication on aquatic organisms [4]. Hypoxia can cause direct mortality, reduced growth rates and altered behaviour and distributions of fish [4] and other organisms. In addition, bottom-water hypoxia can interact with elevated water temperatures at the surface to produce a "temperature-oxygen squeeze" effect, which can greatly reduce the amount of summer habitat available for some species [12]. Eggs and larvae of fish (and crustaceans) may be particularly susceptible to this effect because these life history stages are less able to avoid unfavourable conditions, and because they live in near shore areas, such as estuaries, where too-high water temperatures and too-low oxygen conditions often occur [5]. Changes in fish assemblages and crustaceans in response to hypoxia and & anoxia can render these organisms more susceptible to fishing pressure, and can increase the abundance of non-targeted species in by-catch [4].

Dissolved oxygen status also influences the uptake or release of nutrients from sediment. When oxygen is depleted, the nitrification pathway is blocked, and efficiencies may be lowered. As a consequence, more nutrients (e.g. nitrogen and phosphorous) are released from the sediment in bio-available forms [7]. These nutrients help to sustain algal blooms, and therefore continue the supply organic matter to the sediments [7]. With organic matter (energy) diverted from invertebrate consumption to microbial decomposition, the natural pattern of energy flow is altered, and pelagic and opportunistic species are favoured [8]. Indeed, an increased ratio of planktivore:demersal fish biomass is an important effect of eutrophication [11]. Low bottom water oxygen concentrations are also conducive to the build-up of toxic compounds such as hydrogen sulfide and ammonia gas, which can also be harmful to benthic organisms and fish. Even short-lived anoxic events can cause the mass mortality of fish and benthic organisms [10].

Overall, anoxic and hypoxic events can cause large reductions in the abundance, diversity and harvest of fish in affected waters [4], and can contribute to an overall loss of bio-diversity[9]. However, the extent to which bottom water anoxia causes declines in overall fish production depends on a balanced between the negative and positive and effects of eutrophication in the full spectrum of habitats within the system [4]……

Major research institutions, universities and government (local and State) agencies gather oxygen data for specific research studies. Some information on anoxic and hypoxic events in Australian coastal waterways was compiled during the National Land & Water Resources Audit. In most cases, no data was available. However, localised or short-lived periods of hypoxia were reported in the Derwent and Huon estuaries (TAS) and in the Tuggerah Lakes (NSW). Prolonged and extensive anoxia is experienced in the Gippsland Lakes.

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NSW North Coast

Australian Bureau of Meteorology

Moggy Musings

Hi! My name is Boy. I'm a male bi-coloured tabby cat. Ever since I discovered that Malcolm Turnbull's dogs were allowed to blog, I have been pestering Clarencegirl to allow me a small space on North Coast Voices.

A false flag musing: I have noticed one particular voice on Facebook which is Pollyanna-positive on the subject of the Port of Yamba becoming a designated cruise ship destination. What this gentleman doesn’t disclose is that, as a principal of Middle Star Pty Ltd, he could be thought to have a potential pecuniary interest due to the fact that this corporation (which has had an office in Grafton since 2012) provides consultancy services and tourismbusiness development services.

A religion & local government musing: On 11 October 2017 Clarence Valley Council has the Church of Jesus Christ Development Fund Inc in Sutherland Local Court No. 6 for a small claims hearing. It would appear that there may be a little issue in rendering unto Caesar. On 19 September 2017 an ordained minister of a religion (which was named by the Royal Commission into Institutional Responses to Child Sexual Abuse in relation to 40 instances of historical child sexual abuse on the NSW North Coast) read the Opening Prayer at Council’s ordinary monthly meeting. Earlier in the year an ordained minister (from a church network alleged to have supported an overseas orphanage closed because of child abuse claims in 2013) read the Opening Prayer and an ordained minister (belonging to yet another church network accused of ignoring child sexual abuse in the US and racism in South Africa) read the Opening Prayer at yet another ordinary monthly meeting. Nice one councillors - you are covering yourselves with glory!

An investigative musing: Newcastle Herald, 12 August 2017: The state’s corruption watchdog has been asked to investigate the finances of the Awabakal Aboriginal Local Land Council, less than 12 months after the troubled organisation was placed into administration by the state government. The Newcastle Herald understands accounting firm PKF Lawler made the decision to refer the land council to the Independent Commission Against Corruption after discovering a number of irregularities during an audit of its financial statements.The results of the audit were recently presented to a meeting of Awabakal members. Administrator Terry Lawler did not respond when contacted by the Herald and a PKF Lawler spokesperson said it was unable to comment on the matter. Given the intricate web of company relationships that existed with at least one former board member it is not outside the realms of possibility that, if ICAC accepts this referral, then United Land Councils Limited (registered New Zealand) and United First Peoples Syndications Pty Ltd(registered Australia) might be interviewed. North Coast Voices readers will remember that on 15 August 2015 representatives of these two companied gave evidence before NSW Legislative Council General Purpose Standing Committee No. 6 INQUIRY INTO CROWN LAND. This evidence included advocating for a Yamba mega port.

A Nationals musing: Word around the traps is that NSW Nats MP for Clarence Chris Gulaptis has been talking up the notion of cruise ships visiting the Clarence River estuary. Fair dinkum! That man can be guaranteed to run with any bad idea put to him. I'm sure one or more cruise ships moored in the main navigation channel on a regular basis for one, two or three days is something other regular river users will really welcome. *pause for appreciation of irony* The draft of the smallest of the smaller cruise vessels is 3 metres and it would only stay safely afloat in that channel. Even the Yamba-Iluka ferry has been known to get momentarily stuck in silt/sand from time to time in Yamba Bay and even a very small cruise ship wouldn't be able to safely enter and exit Iluka Bay. You can bet your bottom dollar operators of cruise lines would soon be calling for dredging at the approach to the river mouth - and you know how well that goes down with the local residents.

A local councils musing: Which Northern Rivers council is on a low-key NSW Office of Local Government watch list courtesy of feet dragging by a past general manager?

A serial pest musing: I'm sure the Clarence Valley was thrilled to find that a well-known fantasist is active once again in the wee small hours of the morning treading a well-worn path of accusations involving police, local business owners and others.

An investigative musing: Which NSW North Coast council is batting to have the longest running code of conduct complaint investigation on record?

A which bank? musing: Despite a net profit last year of $9,227 million the Commonwealth Bank still insists on paying below Centrelink deeming rates interest on money held in Pensioner Security Accounts. One local wag says he’s waiting for the first bill from the bank charging him for the privilege of keeping his pension dollars at that bank.

A Daily Examiner musing: Just when you thought this newspaper could sink no lower under News Corp management, it continues to give column space to Andrew Bolt.

A thought to ponder musing: In case of bushfire or flood - do you have an emergency evacuation plan for the family pet?

An adoption musing: Every week on the NSW North Coast a number of cats and dogs find themselves without a home. If you want to do your bit and give one bundle of joy a new family, contact Happy Paws on 0419 404 766 or your local council pound.